The present invention relates to a work holder-tool collision preventing device for use with numerical control equipment for a turret punch press, with which it is possible to prevent a work holder holding a workpiece and a tool from being broken down by a collision therebetween which is caused by an accidental punching operation of the tool to the work holder due to a program error or the like.
In conventional devices of this kind it is customary that a certain region directly specified by a limit switch, parameter setting or a command from a command tape is set up as an axis displacement inhibit region, thereby preventing a tool from colliding against a work holder due to a program error or the like.
However, in the case of using the limit switch, much time is needed for providing the switch and associated works. Also in the cases of the parameter setting and tape command, it is necessary for the operator to establish the inhibit region in advance by computations consuming relatively much time. Moreover, the sizes of tools which are mounted on a turret vary greatly, so that in order to minimize the inhibit region and enlarge a punching region, it is desirable to modify the inhibit region according to the size of the tool selected. However, this cannot easily be done in the case of using the limit switch and in the cases of the parameter setting and tape command, the burden on the operator will increase and a large storage capacity will be needed.